2010 Cadillac CTS Sedan AWD V6-3.6L Page 1077

2010 Cadillac CTS Sedan AWD V6-3.6L Page 1077

Replacement - Bank 1)

* T8 Ignition Coil Replacement - Bank 2 (See: Powertrain Management/Ignition System/Ignition Coil/Service and Repair/Ignition Coil

Replacement - Bank 2)

* Control Module References (See: Testing and Inspection/Programming and Relearning) for K20 ECM replacement, setup, and

programming

P0137

DTC P0137, P0138, P0140, P0157, P0158, or P0160 (With LLT)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

DTC Descriptors

DTC P0137

- HO2S Circuit Low Voltage Bank 1 Sensor 2

DTC P0138

- HO2S Circuit High Voltage Bank 1 Sensor 2

DTC P0140

- HO2S Circuit Insufficient Activity Bank 1 Sensor 2

DTC P0157

- HO2S Circuit Low Voltage Bank 2 Sensor 2

DTC P0158

- HO2S Circuit High Voltage Bank 2 Sensor 2

DTC P0160

- HO2S Circuit Insufficient Activity Bank 2 Sensor 2

Diagnostic Fault Information

Typical Scan Tool Data

Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding

air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the

HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of about 450

mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above

and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control